As a strain gauge type sensor known is a device in which a force or moment is detected by using a semiconductor single crystal substrate. As shown in FIGS. 16 and 17, Patent Document 1 discloses a strain gauge type sensor 500 including a strain generation body 510 made up of a substantially columnar force receiving portion 511 provided at the center, a fixed portion 512 provided around the force receiving portion 511, and an annular diaphragm portion 513 connecting the force receiving portion 511 and the fixed portion 512 to each other; and strain gauges R511 to R534 each made of a piezoresistive element and attached to the strain generation body 510.
The strain gauges R511 to R534 are attached to the upper surface of the strain generation body 510. In this example, the origin O is defined at the point at which the central axis of the force receiving portion 511 intersects with the upper surface of the strain generation body 510. The X- and Y-axes are defined as two axes that extend perpendicularly to each other on the upper surface of the strain generation body 510 through the origin O. In addition, an oblique axis S is defined on the upper surface of the strain generation body 510 so as to extend through the origin O differently from any of the X- and Y-axes. The strain gauges R511 to R534 are disposed on the respective axes near the outer and inner edges of the diaphragm portion 513.
In the strain gauge type sensor 500, the strain gauges R511 to R534 constitute bridge circuits for measuring three-axial forces or moments on the X-, Y-, and Z-axes applied to the force receiving portion 511. More specifically, the strain gauges R511 to R514 on the X-axis constitute a bridge circuit 521 as shown in FIG. 18A to obtain a voltage Vx. The strain gauges R521 to R524 on the Y-axis constitute a bridge circuit 522 as shown in FIG. 18B to obtain a voltage Vy. Further, the strain gauges R531 to R534 on the S-axis constitute a bridge circuit 523 as shown in FIG. 18C to obtain a voltage Vz. By combination of the voltages Vx, Vy, and Vz obtained by the bridge circuits 521 to 523, three-axial forces or moments on the X-, Y-, and Z-axes applied to the force receiving portion 511 can be calculated.
Patent Document 1: JP-A-4-194634 (FIG. 2; FIG. 3; FIG. 7; page 3, lower left column, line 3 to lower right column, line 6; and page 4, lower right column, lines 9 to 15)